iPad isn't detecting an external monitor unless it's plugged into a power source

Hello Everyone

I have ipad 11 Pro 3rd Gen iOS 18.1.1

When I am trying to connect my ipad to external monitor, it is NOT getting connected unless I connect ipad charger to HDMI hub as show me the photo (USB-C port the ipad charger). Once I remove the charger, the external display is getting automatically disconnected, even though the HDMI connection is still on.

However, when I am trying to connect my iPhone 15 Pro Max (iOS 18.1) to the same hub even WITHOUT plugging in the charger, external display is getting connected immediately.

My external monitor has its own power brick, so I dont think it has anything to do with the battery of ipad or iphone.

Kindly provide solution.